The present invention relates to a rolling mill equipped with an on-line roll grinding system, and more particularly to an on-line roll grinding system for effectively grinding mill rolls on-line without undergoing influences of vibration of work rolls.
Generally, when slabs are rolled by work rolls of a strip rolling mill, there occurs a periphery difference between the rolling zone and the unrolling zone because only the former is abraded or worn away. This imposes such restrictions upon the rolling operation as necessity of rolling slabs in order of wide ones to narrow ones. To solve that problem, there have been proposed various techniques and control methods in relation to on-line roll grinders.
For example, "Development of On-Line Roll Grinders", Mitsubishi Giho, Vol. 25, No. 4, 1988, discloses a technique that a plurality of cup grinding stones are arranged along one work roll and mounted to a one-piece frame, the frame being always moved in its entirety over a certain range, and the cup grinding stones are not positively driven to rotate but passively driven with the aid of torque of the work roll, thereby grinding the entire surface of the work roll (hereinafter referred to as first prior art).
Also, JP, U, 58-28705 discloses a technique that one roll grinding unit is disposed for one work roll, contact rolls serving as position sensors are held in contact with neck portions at both ends of the work roll on the side thereof opposite to the roll grinding unit, the position sensors detecting an offset of the work roll, and a shifting device is controlled to move a grinding wheel following the detected offset (hereinafter referred to as second prior art).
Further, "On-Line Constant Pressure Grinding for Work Rolls", Proceedings of 1992 Spring Lecture Meeting of Precision Engineering Society of Japan, reports an experimental result of forming an abrasive layer of a cup grinding stone using abrasives of cubic boron nitride (CBN), arranging a spindle of the grinding stone perpendicularly to the axis of a work roll, and grinding the work roll (hereinafter referred to as third prior art).
In addition, JP, U, 58-28706 and JP, U, 62-95867 disclose a technique that a cup grinding stone arranged substantially perpendicular to a work roll is mounted to a spindle slidably in its axial direction, and the grinding stone is axially supported at its backside by an elastic body directly or via a boss, thereby absorbing vibration of the work roll (hereinafter referred to as fourth prior art).
Meanwhile, in strip rolling machines, it has been conventionally proposed to measure the profile of a work roll and control the crown and shape of a strip by utilizing the measured profile. As a technique for measuring the profile of the work roll, an on-line roll profile meter has been developed which employs a ultrasonic profile meter. The system configuration of this profile meter is described in "Development of On-Line Roll Grinding System with Profile Meter", Mitsubishi Giho, Vol. 29, No. 1, 1992. In this system, a column of water is produced between a probe with a ultrasonic profile meter built therein and a work roll, and the spacing from the probe to the work roll is determined based on the time required for pulsatory ultrasonic waves emitted from the probe to reciprocate between the probe and the surface of the work roll (hereinafter referred to as fifth prior art).